A currently-used coating apparatus includes a nozzle dispensing chemical such as a resist liquid to a substrate, a resist pipe in communication with the nozzle, and a pump that sucks up the chemical from a chemical container that stores a coating liquid and feeds out the chemical through the resist pipe. In addition, the resist pipe includes an open/close valve between the nozzle and the pump for opening/closing the resist pipe to selectively dispense and stop dispensation of the chemical from the nozzle. Moreover, a foreign substance removable filter is provided between the open/close valve and the pump for removal of foreign substances. See, for example, Patent Literature 1. Furthermore, a suck back valve is optionally provided between the nozzle and the open/close valve. See, for example, Patent Literature 2.
Here, a long distance between the foreign substance removable filter and the nozzle may cause generation of additional foreign substances in the chemical after the foreign substance removable filter removes the foreign substances. Accordingly, the foreign substance removable filter is desired to be inserted adjacent to the nozzle as possible. Patent Literature 3 discloses a feature of a foreign substance removable filter between the nozzle and the open/close valve. However, the feature may cause a problem of dripping (or drop) that the chemical drips down from the nozzle. The dripping chemical leads to uneven coating and some defective products.
Specifically, the supplied chemical is under pressure in the foreign substance removable filter even when the open/close valve is closed while the nozzle dispenses the chemical. Accordingly the chemical is dispensed for a while in an open/close valve closed condition due to a residual pressure in the foreign substance removable filter. This causes the dripping. Then, Patent Literature 3 discloses a suck back valve used for avoiding the dripping.
Here, FIG. 8 illustrates principal parts of a currently-used coating apparatus. The coating apparatus of FIG. 8 includes an open/close valve 235 and a suck back valve 247 each driven through air supply. Here, the air supply is performed by adjusting a flow rate of air from an air supplying source 295 with speed controllers 266 and 276. The open/close valve 277 selectively supplies and stops the air supply. The open/close valve 277 is controlled with a controller 251.